Dirty Scratching/Clicking Sound on one channel [resolved]

[Andrew Lee Rubinger]

Hi all:

I'm getting a clicking and scratching sound out of one channel:

 

When I touch the outside of the power transformer as shown, it goes away.  Any ideas what I might check, or is there a chance the transformer itself has gone bad?

S,
ALR

[Paul Birkeland]

Tighten your transformer screws.  If that doesn't do it, but an outlet tester for your outlet (the one with the 3 lights) and check its functionality.

-PB

[Andrew Lee Rubinger]

Thanks.  Tightened up and the outlet is all good; also the issue persists in some other outlets both directly plugged in and behind power conditioners.

Any other advice I might try next?  Appreciated!

S,
ALR

[Grainger49]

   .  .  .    the issue persists in some other outlets  .  .  .  . 

Are there outlets you have tried feeding your BeePre that it doesn't happen?

I would try taking a jumper to one of the screws on the transformer, preferably the one where the ground wire is, and take the other end to the top plate.  We are trying to verify that grounding the transformer mounting hardware has something to do with it.

[Andrew Lee Rubinger]

Thanks; I would have suspected some grounding too.  Checked the connection there, and also did the jumping as you've suggested just now.  Issue persists.  Some additional context: I actually don't have to TOUCH the transformer to make the sound go away; simply placing my hand there about an inch away will do the trick.

S,
ALR

[Grainger49]

    .  .  .    I actually don't have to TOUCH the transformer to make the sound go away; simply placing my hand there about an inch away will do the trick  .  .  .  .   

This sounds like a ground loop problem. 

What is your answer to the question about your use of "some" in your previous post?

[Andrew Lee Rubinger]

A ground loop problem in just one channel?

Oh, I didn't try ALL the outlets in my house.  Just some.  And the set of outlets that I tried is equal to the set of outlets which presents the problem

S,
ALR

[Andrew Lee Rubinger]

I might also ask:  how does one solve a ground loop problem, if this is what it is?

S,
ALR

[Grainger49]

It is a long hunt.

[Andrew Lee Rubinger]

Just doesn't add up; it doesn't sound like ground loop hum, explain why I only observe it in one channel, or why my hand near the power transformer would quell the sound.  Right?

[Doc B.]

Have you tried swapping tubes from side to side to see if it follows a tube?

[Andrew Lee Rubinger]

Yup, swapped the 300Bs and the input tubes as well; right channel only remains affected.

[Andrew Lee Rubinger]

Solved.  Thanks everyone for your input.

My hand by the power transformer making the issue go away was because it was disrupting a magnetic field given off by the output transformer of my power amp, adjacent to it.  Moving the two physically apart and askew a bit separated 'em enough to make the interference go away.

How about that?

S,
ALR

[Grainger49]

Good sleuthing!